003 Operating System Verified Copy

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8. What are the typical elements of a process image?

User data: Modifiable part of user space. May include program data, user stack area, andprograms that may be modified.

User program: The instructions to be executed. System Stack: Each process has one or more LIFO stacks associated with it. Used to store

parameters and calling addresses for procedure and system calls.

Process control Block (PCB): Info needed by the OS to control processes.

9. What is the Translation Lookaside Buffer (TLB)?In a cached system, the base addresses of the last few referenced pages is maintained in

registers called the TLB that aids in faster lookup. TLB contains those page-table entries that havebeen most recently used. Normally, each virtual memory reference causes 2 physical memoryaccesses-- one to fetch appropriate page-table entry, and one to fetch the desired data. Using TLB in-

between, this is reduced to just one physical memory access in cases of TLB-hit.

10.What is the resident set and working set of a process?Resident set is that portion of the process image that is actually in real-memory at a particular

instant. Working set is that subset of resident set that is actually needed for execution. (Relate this tothe variable-window size method for swapping techniques.)

11.When is a system in safe state?The set of dispatchable processes is in a safe state if there exists at least one temporal order in

which all processes can be run to completion without resulting in a deadlock.

12.What is cycle stealing?We encounter cycle stealing in the context of Direct Memory Access (DMA). Either the DMA

controller can use the data bus when the CPU does not need it, or it may force the CPU to temporarilysuspend operation. The latter technique is called cycle stealing. Note that cycle stealing can be done

only at specific break points in an instruction cycle.

13.What is meant by arm-stickiness?If one or a few processes have a high access rate to data on one track of a storage disk, then

they may monopolize the device by repeated requests to that track. This generally happens with mostcommon device scheduling algorithms (LIFO, SSTF, C-SCAN, etc). High-density multisurface disksare more likely to be affected by this than low density ones.

14.What is busy waiting?The repeated execution of a loop of code while waiting for an event to occur is called busy-

waiting. The CPU is not engaged in any real productive activity during this period, and the processdoes not progress toward completion.


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15.Explain the popular multiprocessor thread-scheduling strategies.

Load Sharing: Processes are not assigned to a particular processor. A global queue of threads ismaintained. Each processor, when idle, selects a thread from this queue. Note that load

balancing refers to a scheme where work is allocated to processors on a more permanent basis. Gang Scheduling: A set of related threads is scheduled to run on a set of processors at the same

time, on a 1-to-1 basis. Closely related threads / processes may be scheduled this way to reduce

synchronization blocking, and minimize process switching. Group scheduling predated thisstrategy. Dedicated processor assignment: Provides implicit scheduling defined by assignment of threads

to processors. For the duration of program execution, each program is allocated a set ofprocessors equal in number to the number of threads in the program. Processors are chosenfrom the available pool.

Dynamic scheduling: The number of thread in a program can be altered during the course ofexecution.

16.When does the condition 'rendezvous' arise?In message passing, it is the condition in which, both, the sender and receiver are blocked until

the message is delivered.

17.What is a trap and trapdoor?Trapdoor is a secret undocumented entry point into a program used to grant access without

normal methods of access authentication. A trap is a software interrupt, usually the result of an errorcondition.

18.What are local and global page replacements?Local replacement means that an incoming page is brought in only to the relevant process'

address space. Global replacement policy allows any page frame from any process to be replaced. Thelatter is applicable to variable partitions model only.

19.Define latency, transfer and seek time with respect to disk I/O.Seek time is the time required to move the disk arm to the required track. Rotational delay or

latency is the time it takes for the beginning of the required sector to reach the head. Sum of seek time(if any) and latency is the access time. Time taken to actually transfer a span of data is transfer time.

20.Describe the Buddy system of memory allocation.Free memory is maintained in linked lists, each of equal sized blocks. Any such block is of size

2^k. When some memory is required by a process, the block size of next higher order is chosen, andbroken into two. Note that the two such pieces differ in address only in their kth bit. Such pieces arecalled buddies. When any used block is freed, the OS checks to see if its buddy is also free. If so, it isrejoined, and put into the original free-block linked-list.

21.What is time-stamping?It is a technique proposed by Lamport, used to order events in a distributed system without the

use of clocks. This scheme is intended to order events consisting of the transmission of messages. Eachsystem 'i' in the network maintains a counter Ci. Every time a system transmits a message, itincrements its counter by 1 and attaches the time-stamp Ti to the message. When a message isreceived, the receiving system 'j' sets its counter Cj to 1 more than the maximum of its current valueand the incoming time-stamp Ti. At each site, the ordering of messages is determined by the followingrules: For messages x from site i and y from site j, x precedes y if one of the following conditions

holds....(a) if Ti


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22.How are the wait/signal operations for monitor different from those for semaphores?

If a process in a monitor signal and no task is waiting on the condition variable, the signal islost. So this allows easier program design. Whereas in semaphores, every operation affects the value ofthe semaphore, so the wait and signal operations should be perfectly balanced in the program.

23.In the context of memory management, what are placement and replacement algorithms?

Placement algorithms determine where in available real-memory to load a program. Commonmethods are first-fit, next-fit, best-fit. Replacement algorithms are used when memory is full, and oneprocess (or part of a process) needs to be swapped out to accommodate a new program. Thereplacement algorithm determines which are the partitions to be swapped out.

24.In loading programs into memory, what is the difference between load-time dynamic

linking and run-time dynamic linking?For load-time dynamic linking: Load module to be loaded is read into memory. Any reference

to a target external module causes that module to be loaded and the references are updated to a relativeaddress from the start base address of the application module.

With run-time dynamic loading: Some of the linking is postponed until actual reference during

execution. Then the correct module is loaded and linked.

25.What are demand- and pre-paging?With demand paging, a page is brought into memory only when a location on that page is

actually referenced during execution. With pre-paging, pages other than the one demanded by a pagefault are brought in. The selection of such pages is done based on common access patterns, especiallyfor secondary memory devices.

26.Paging a memory management function, while multiprogramming a processor

management function, are the two interdependent?Yes.

27.What is page cannibalizing?Page swapping or page replacements are called page cannibalizing.

28.What has triggered the need for multitasking in PCs?

Increased speed and memory capacity of microprocessors together with the support firvirtual memory and

Growth of client server computing

29.What are the four layers that Windows NT have in order to achieve independence?

Hardware abstraction layer

Kernel Subsystems System Services.

30.What is SMP?To achieve maximum efficiency and reliability a mode of operation known as symmetric

multiprocessing is used. In essence, with SMP any process or threads can be assigned to any processor.

31.What are the key object oriented concepts used by Windows NT? Encapsulation

Object class and instance


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32.What is a drawback of MVT?

It does not have the features like ability to support multiple processors virtual storage source level debugging

33.

What is process spawning?When the OS at the explicit request of another process creates a process, this action is calledprocess spawning.

34.How many jobs can be run concurrently on MVT?15 jobs

35.List out some reasons for process termination. Normal completion Time limit exceeded Memory unavailable

Bounds violation Protection error Arithmetic error Time overrun I/O failure Invalid instruction Privileged instruction Data misuse Operator or OS intervention Parent termination.

36.

What are the reasons for process suspension? swapping interactive user request timing parent process request

37.What is process migration?It is the transfer of sufficient amount of the state of process from one machine to the target

machine

38.What is mutant?In Windows NT a mutant provides kernel mode or user mode mutual exclusion with the notion

of ownership.

39.What is an idle thread?The special thread a dispatcher will execute when no ready thread is found.

40.What is FtDisk?It is a fault tolerance disk driver for Windows NT.


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41.What are the possible threads a thread can have?

Ready Standby Running Waiting Transition

Terminated.

42.What are rings in Windows NT?Windows NT uses protection mechanism called rings provides by the process to implement

separation between the user mode and kernel mode.

43.What is Executive in Windows NT?In Windows NT, executive refers to the operating system code that runs in kernel mode.

44.What are the sub-components of I/O manager in Windows NT?

Network redirector/ Server

Cache manager. File systems Network driver Device driver

45.What are DDks? Name an operating system that includes this feature.DDks are device driver kits, which are equivalent to SDKs for writing device drivers. Windows

NT includes DDks.

46.What level of security does Windows NT meets?C2 level security.


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1. Information about a process is maintained in a _________.

a) Stack. b) Translation lookaside buffer.c) Process control block. d) Program control block.

2. Identify the odd thing in the services of operating system?

a)

Accounting. b) Protection.c) Virus detection. d) Dead lock handling.

3. Which of the following is not advantage of multiprogramming?a) Increased throughput. b) Shorter response time.c) Decreased operating system overhead. d)Ability to assign priorities to jobs.

4. Real time systems are ________.a) primarily used on mainframe computers. b) used for monitoring events as they occur.c) used for program development. d) used for real time interactive users.

5. Which is not an Operating System?a)Windows 95. b) MS-DOS.c) Windows 3.1. d) Windows 2000.


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6. Who is called a supervisor of computer activity?a)CPU. b) Operating system.c) Control unit. d)Application Program.

7. The process related to process control, file management, device management, information

about system and communication that is requested by any higher level language can be

performed by ___

a) Editors. b) Compilersc) System call. d) Caching.

8. Multiprocessing ________.a) Make the operating system simpler.

b) Allows multiple processes to run simultaneously.c) Is completely understood by all major computer vendors.d) Allows the same computer to have the multiple processors.

9. _______ operating system pays more attention on the meeting of the time limits.

a) Distributed. b)Network.

c) Real time. d) Online.

10.Which of the following is an example of a SPOOLED device?a) The terminal used to enter the input data for a program being executed.

b)The secondary memory device in a virtual memory system.c) A line printer used to print the output of a number of jobs.d) The terminal used to store data permanently.

11.Overlay is _______________.a) A part of an operating system.

b) A specific memory location.

c) A single contiguous memory that was used in the olden days for running large.d) Overloading the system with many user files.

12.Working set(t,k) at an instance of time t, is the set of _______.a) A k future references that the operating system will make.

b) B. future references that the operating system will make in the next k time units.c) C. k references with high frequency.d)

D. pages that have been referenced in the last k time units.


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13.Kernel is _______.

a) Considered as the critical part of the operating system.b) The software which monitors the operating system.c) The software which protects all programs.d) The set of primitive functions upon which the rest of operating system functions are built up.

14.

Supervisor call _______.a) Is a call made by the supervisor of the system.b) Is a call with control functions.c) Are privileged calls that are used to perform resource management functions which are

Controlled by the operating system.d) Is a call made by someone working in root directory?

15.Memory protection is used in a ________.a) single user system. b) Multiprogramming system.c) Multitasking system. d) Real time systems.

16.

Some computer systems support dual mode operation-the user mode and the supervisoror monitor mode. These refer to the modes ______.a) by which user programs handle their data.

b) by which the operating system executes user programs.c) in which the processor and the associated hardware operate.d) by memory access.

17.Which of the following is a service not supported by the operating system?a)Protection. b) Accounting.c) Compilation. d) I/O operation.

18.

Which of the following are single user operating system?a) MS-DOS. b) UNIX. c) LINUX. d) OS/2.

19.Which of the following are true?a. A re-entrant procedure can be called any number of times.

b. A re-entrant procedure can be called finite number of times.c. A re-entrant procedure cannot be called recursively.d. A re-entrant procedure can be called recursively.

20.In a multi-user operating system, 20 requests are made to use a particular resource per

hour, on an average. The probability that no requests are made in 45 minutes is ____a) e-15. b) e-5. c) 1 - e-5. d)1 - e-10.

21.To obtain better memory utilization, dynamic loading is used. With dynamic loading, a

routine is not loaded until it is called for. For implementing dynamic loading, _______.a)

special support from hardware is essential.b)

special support from operating system is essential.c) special support from both hardware and operating system is essential.d)

user programs can implement dynamic loading without any special support from theoperating system or the hardware.


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22.Which of the following is true?

a) The linkage editor is used to edit programs which have to be later linked together.b) The linkage editor links object modules during compiling or assembling.c) The linkage editor links object modules and resolves external references between them

before loading.d) The linkage editor resolves external references between the object modules during

execution time.

23.Distributed systems should ________.a) Meet prescribed time constraints. b) Aim better resource sharing.c) Aim better system utilization. d) Aim low system overhead.

24.Memory protection is normally done by the ________.a)

Processor and the associated hardware. b) Operating system.c) Compiler. d)user program.

25.When an interrupt occurs, an operating system __________.

a)

ignores the interrupt.b)

always changes the state of the interrupted process after processing the interrupt.c) always resumes execution of the interrupted process after processing the interrupt.d)

may change the state of the interrupted process to blocked and schedule another process.

26.Protection can improve _____.a) Reliability. b)Maintenance. c) Starvation. d)Deadlock.

27.A system consists of collection of ______.

a) Processes. b) software. c) Database. d)Printer.

28.The startup routine runs, when machine boots up is known as ______.a) POST b) BOOT up . c) Operating Routine . d)I/O operation .

29.What is the maximum length allowed for primary name of a computer file under DOS?a) 8 b)12 c)15 d)30

30.Which of the following could be a valid DOS file specification?a)

NOSFILE.POST. b)NOSFILE.P.OST.c)NOSFILE.DOC. d)NOST.FILEDOC.

31.

How many characters form a secondary name for a file?a) 8. b)12. c) 13. d)25.

32.What is the name given to something that the computer will automatically use unless you

tell itotherwise?a) A Specification. b)A Wildcard. c)A Default. d)A Rule.

33.The batch file uses the extension _______.a) BAT b)DOC c) PRG d)DOS


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34.To display the list of all the file of the disk you would type _______.

a) DIR. b)COPY. c)DIR FILES. d)DIR AUTOEXEC.BAT.

35.______runs on computer hardware and serve as platform for other software to run on.a)

Operating system. b)Application software.c)System software. d)Compiler

36.The primary purpose of an operating system is _____.a)

to make the most efficient use of the computer hardware.b) to allow people to use the computer.c) to keep systems programmers employed.d) to make computers easier to use.

37._______transforms one interface into another interface.a) Program. b)Software. c)Data. d)Hardware.

38.__ interface consists of things like program counter, registers, interrupts and terminals.

a)

Hardware. b)Software. c)Data. d)Application.

39.PID is used by the system to identify _______.a)

a process. b)the file name. c)the i-node. d)The hardware.

40._____is used in operating system to separate mechanism from policy.a) Single level implementation. b) Two level implementation.c) Multi level implementation. d)Hierarchical implementation.

41.The operating system creates ____ from the physical computer.a) Virtual space. b)Virtualcomputers.

c)Virtual device. d)Virtual memory.

42.Which of the following operating does not implement multitasking truly?a)

Windows 98 b) Windows NT.c) Windows XP. d) MS DOS.

43.What is the name of the latest server operating system developed by Microsoft?a) Windows NT. b)Windows 2000c) Windows XP. d) Windows Server 2012 R2

44.Where do you find user.dat?a)

C:\windows. b)C:\windows\system32.c)C:\windows\system. d)C:\.

45.MSD.exe does not have information on _______.a)

Cache b) Video.c) Operating system. d)Com or port.


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46.Which file in MSDOS contain internal command that is loaded during booting process?

a) IO.sys. b)MSDOS.sys.c)Command.com. d)Config.sys.

47.Which is valid extension that user creates on operating system?a) Exe b)Com

b)

Sys d)Bat

48.Which of the following file names are invalid in MSDOS?a) MYFILE.DOS. b)CHECK$.(1).c)Verified.###. d)Qwerty.1?3.

49.Which of the following statements in regard to directories is false?a)

Directories can exist inside directories.b) Directory is always at the highest level.c)

Directories with files can be deleted.d) Directories cannot be renamed.

50.The request and release of resources are ___________.a) command line statements. b)interrupts.c)system calls. d)special programs.

99.The Hardware mechanism that enables a device to notify the CPU is called ____a)

Polling. b)Interrupt.c) System Call. d) System request.

100. The operating system manages ________.

a)

Memory. b)Processor.c)Disk and I/O devices. d)All of the above.

101. The primary job of the operating system of a computer is to ________.a) Command Resources. b) Manage Resources.c) Provide Utilities. d) Be user friendly.

102.CPU performance is measured through ________.a) Throughput. b) Mhz.c) Flaps. d) Flips.

103.Technique to discover hardware status by repeatedly testing each device is _______.a)

Piping . b) Polling.c)dispatching. d)interrupting.

104. _____ indicate that an error has occurred, either is hardware or as a result of a software

instruction.a)

Quantum. b)Exception.c) Interrupt. d)Dispatching.

105. ________ correspond to conditions such as overflows or breakpoints.

a)

Fault. b)Trap.c) Abort. d)Error.


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106. ______ indicate errors from which the process cannot recover, such as hardware failure.a) Fault .b)Trap. c) Abort. d)Exception.

107. A kernel code that is executed in response to an interrupt is _____.a) Interrupt handler. b) interrupt vector.c) interval timer. d) interrupting clock.

108. The part of machine level instruction, which tells the central processor what has to bedone, isa)

Operation code b)Addressc)Locator d)Flip-Flope) None of the above

109. Which of the following refers to the associative memory?a)

the address of the data is generated by the CPUb) the address of the data is supplied by the usersc)

there is no need for an address i.e. the data is used as an addressd) the data are accessed sequentially

e)

None of the above

110. A system program that combines the separately compiled modules of a program into a

formsuitable for executiona) Assembler b)linking loaderc)cross compiler d)load and go e)None of the above

111. A computer cannot "boot" if it does not have thea) Compiler b)Loader c)Operating system

d)Assembler e)None of the above

112. Which of the following functions is(are) performed by the loadera)

allocate space in memory for the programs and resolve symbolic references between objectdecks

b)

adjust all address dependent locations, such as address constants, to correspond to the allocatedspace.

c) physically place the machine instructions and data into memory.d) All of the abovee) None of the above

113. User-Friendly Systems are:a)

required for object-oriented programmingb)

easy to developc)

common among traditional mainframe operating systemsd) becoming more commone)

None of the above

114. What is the name given to the organized collection of software that controls the overalloperation of a computer?

a) Working system b)Peripheral system c)Operating systemd)Controlling system e)None of the above


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115. Which of the following are(is) Language Processor(s)

a)

assembles b)compilers c)interpretersd)All of the above e)None of the above

116. Bug means

a) A logical error in a programb)

A difficult syntax error in a programc) Documenting programs using an efficient documentation toold)

All of the abovee) None of the above

117. An algorithm is best described asa) A computer language b)A step by step procedure for solving a problemc) A branch of mathematics d)All of the abovee) None of the above

118. Trojan-Horse programs

a) are legitimate programs that allow unauthorized access

b) do not usually work

c)

are hidden programs that do not show up on the systemd) usually are immediately discoverede)

None of the above

119. When did IBM release the first version of disk operating system DOS version 1.0?a) 1981 b)1982 c)1983 d)1984 e)None of the above

120. Most of the microcomputer's operating systems like Apple DOS, MS DOS and PC DOS

etc. are called disk operating systems becausea)

they are memory resident b)they are initially stored on diskb) they are available on magnetic tapes

c)

they are partly in primary memory and partly on diskd) None of the above

121. Operating systema) links a program with the subroutines it references

b) provides a layered, user-friendly interfacec)

enables the programmer to draw a flowchartd) all of the abovee)

None of the above

122. Software that measures, monitors, analyzes, and controls real-world events is called:

a)

system software b)real-time softwarec) Scientific software d)business software e)None of the above

123. The details of all external symbols and relocation formation (relocation list or map) is

provided to linker bya)

Macro processor b)Translator c)Loaderd)Editor e)None of the above

124. The macro processor must perform

a) recognize macro definitions and macro callsb) save the macro definitionsc) expand macros calls and substitute arguments

d)

all of the abovee) None of the above


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125. Which of the following is helpful in evaluating applications software what will best suit

your needs?a) recommendations by other users b)computer magazinesc) Objective software reviews d) all of the abovee) None of the above

126. System programs such as Compilers are designed so that they area) reenterable b)non reusablec) serially usable d)recursivee) None of the above

127. IBM released its first PC in 1981. Can you name the operating system which was most

popular at that time?a)

MS-DOS b)PC-DOSc) OS/360 d)CP/M e)None of the above

128. A translator is best described as

a)

an application software b)a system softwarec) a hardware component d)all of the above e)None of the above

129. Data encryptiona) is mostly used by public networks

b)

is mostly used by financial networksc) cannot be used by private installationsd)

is not necessary, since data cannot be interceptede) None of the above

130. What is the name given to the process of initializing a microcomputer with its operating

system?

a)

Cold booting b)Booting c)Warm bootin d)Boot recordinge) None of the above

131. The function(s) of the Storage Assignment is (are)a) to assign storage to all variables referenced in the source program.

b) to assign storage to all temporary locations that are necessary for intermediate results.c) to assign storage to literals, and to ensure that the storage is allocate and appropriate locations

are initialized.d) all of the abovee) None of the above

132. A Processora)

is a device that performs a sequence of operations specified by instructions in memory.b) is the device where information is storedc)

is a sequence of instructionsd)

is typically characterized by interactive processing and time of the CPU's time to allow quickresponse to each user.

e)

None of the above


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133. With MS-DOS which command will divide the surface of the blank floppy disk into

sectors and assign a unique address to each one?a) FORMAT command b)FAT command c)VER commandd) CHKDSK command e)None of the above

134. Multiprogramming

a)

is a method of memory allocation by which the program is subdivided into equal portions, orpages and core is subdivided into equal portions or blocks.b)

consists of those addresses that may be generated by a processor during execution of acomputation.

c) is a method of allocating processor time.d) allows multiple programs to reside in separate areas of core at the time.e) None of the above

135. A translator which reads an entire programme written in a high level language and

converts it into machine language code is:a) Assembler b)translator c)compiler

d) system software e)None of the above

136. The advantage(s) inherent to using high level languages is (are)a)

Fewer people, less management and shorter transition in learning timeb) Improved debugging capability, and superior documentationc)

A greater degree of machine independenced) All of the abovee)

None of the above

137. ______________ do not change.a) Dynamic priority. b) Static ram. c) Static priority. d) Dynamic ram.

138. Dynamic priority mechanisms are responsive to ____.a) no change. b)change. c)rapid attention. d)low attention.

139. The action of parsing the source program into the proper syntactic classes is known as

a) syntax analysis b)lexical analysis c)interpretation analysisd)general syntax analysis e)None of the above

140. Which, of the following is not true about the description of a decision table?a) A decision table is easy to modify

b)

A decision table is directly understood by the computerc)

A decision table is easy to understandd)

All of the abovee) None of the above

141. Which is a permanent database in the general model of compiler?a) Literal Table b)Identifier Tablec)Terminal Table d)Source code d)None of the above


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142. What is the name of the technique in which the operating system of a computer executes

several programs concurrently by switching back and forth between them?a) Partitioning b)Multitasking c)Windowing d)Paginge) None of the above

143. A development strategy whereby the executive control modules of a system are coded and

tested first, is known asa) Bottom-up development b)Top-down development c)Left-Right developmentd) All of the above e)None of the above

144. Which table is a permanent database that has an entry for each terminal symbol.a) Terminal table b)Literal table c)Identifier tabled) Reductions e)None of the above

145. The function(s) of the Syntax phase is(are)a)

to recognize the major constructs of the language and to call the appropriate action routines thatwill generate the intermediate form or matrix for these constructs.

b)

to build a literal table and an identifier tablec)

to build a uniform symbol tabled) to parse the source program into the basic elements or tokens of the language.e)

None of the above

146. Inter process communication can be done through __________.a) Mails. b) Messages. c) System calls. d) Traps.

147. A process is starved if __________.

a) it is permanently waiting for a resource. b)semaphores are not used.c) a queue is not used for scheduling. d)demand paging is not properly implemented.

148. CPU performance is measured through ________.a) throughput. b)mhz. c)flaps. d)hz.

149. A program under execution is called ________.

a) dynamic program. b)static program. c)binded program. d)a process.

150. Process said to be in ___________ state if it was waiting for an event that will never occur.a) safe. b)unsafe. c)starvation. d)dead lock.

151. The removal of process from active contention of CPU and reintroduce them into memory

later is known as ____________.a)

Interrupt. b)Swapping. c)Signal. d)Thread.

152. Which technique was introduced because a single job could not keep both the CPU and the

I/O devices busy?a) Time-sharing. b)Spooling.c)Preemptive scheduling. d)Multiprogramming.

153. The state of a process after it encounters an I/O instruction is __________.a) ready. b) blocked/waiting c)idle. d)running.


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154. CPU Scheduling is the basis of _________ operating system.a) Batch. b) real time.c) Multiprogramming. d)monoprogramming.

155. The technique, for sharing the time of a computer among several jobs, which switches jobs

so rapidly such that each job appears to have the computer to itself, is called _______________.a) time sharing. b)time out.

c)time domain. d)multitasking.156. The strategy of making processes that are logically runnable to be temporarily suspended iscalled__________

a) Non preemptive scheduling b)Preemptive schedulingc) Shortest job first d) First come First served

157. Situations where two or more processes are reading or writing some shared data and the

final results depend on the order of usage of the shared data, are called ________.a) Race conditions. b) Critical section.c) Mutual exclusion. d) Dread locks.

158. Which technique was introduced because a single job could not keep both the CPU and theI/O devices busy?

a) Time-sharing. b) Spooling.c) Preemptive scheduling. d)Multiprogramming.

159. In the multi-programming environment, the main memory consisting of _________ number

of process.a)

Greater than 100. b)Only one. c) Greater than 50. d) More than one.

160. Which of the following system calls transforms an executable binary file into a process?a) Fork. b)Exec. c) Ioct1. d)Longjmp.

161. Concurrent processes are processes that ____________.a) do not overlap in time.

b)

overlap in time.c) are executed by a processor at the same time.d) are executed by a processor at the variable time period.

162. The only state transition that is initiated by the user process itself is _______.a) block. b)dispatch. c)wakeup. d)batch.

163. An operating system contains 3 user processes each requiring 2 units of resource R. the

minimum number of units of R such that no deadlock will ever occur is ______.a)

3. b)4. c)5. d)7.

164. In a time-sharing operating system, when the time slot given to a process is completed, the

process goes from the RUNNING state to the ______.a)

BLOCKED state. b)READY state.c) SUSPENDED state. d)TERMINATED state.

165. Which of the following algorithms tends to minimize the process flow time ?a)

First come First serve b)Shortest Job Firstc) Earliest Deadline First d)Longest Job First


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166. Which of the following algorithms tends to minimize the process flow time ?

a) First come First served b)Shortest Job Firstc) Earliest Deadline First d)Longest Job First

167. Under multiprogramming, turnaround time for short jobs is usually ________ and that for

long jobs is slightly ___________.a) Lengthened; Shortened b)Shortened; Unchanged

c) Shortened; Shortened d)Shortened; Lengthened

168. Pre-emptive scheduling, is the strategy of temporarily suspending a running process ______.a) Before the cpu time slice expires. b) To allow starving processes to run.c) When it requests i/o. d) When overflow occurs.

169. If we preempt a resource from a process, the process cannot continue with its normal

execution and it must be ____________.a) Aborted b)queuedc) rolled back d)terminated

170. In round-robin CPU scheduling, as the time quantum is increased, the average turn aroundtime_________.

a) increases. b)decreases.c)remains constant. d) varies irregularly.

171. In a multiprogramming environment _______. .a)

the processor executes more than one process at a time.b) the programs are developed by more than one program.c)

more than one process resides in the memory.d) a single user can execute many programs at the same time

172. In which of the following scheduling policies does context switching never take place?a) Round-robin. b) Shortest job first.c)Pre-emptive. d) Optimal based.

173. Suppose that a process is in BLOCKED state waiting for some I/O service. Which the

service is completed, it goes to the _______.a)

RUNNING state. b) READY state.c) SUSPENDED state. d)TERMINATED state.

174. Cascading termination refers to termination of all child processes before the parent

terminates ___

a)

Normally. b)Abnormally.c) Normally or abnormally. d)In middle of its execution.

175. For implementing a multiprogramming operating system ________.a) Special support from processor is essential.

b) Special support from processor is not essential.c)

Cache memory must be available.d) More than one processor must be available.


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176. Consider a system having m resources of the same type. These resources are shared by 3

processes A,B, C, which have peak time demands of 3, 4, 6 respectively. The minimum value of m

that ensures that deadlock will never occur is ________.a) 11 b)12 c)13 d)14

177. A system has 3 processes sharing 4 resources. If each process needs a maximum of 2 units

then,deadlock ______.a) can never occur. b)may occur. c)has to occur. d)chance of occurrence.

178. If the resources are always preempted from the same process, __________ can occur.a) deadlock b)system crash c)aging d)starvation

179. Which of the following scheduling algorithm gives minimum average waiting time?a) FCFS. b)SJF. c)Round-robin. d)Priority.

180.An optimal scheduling algorithm in terms of minimizing the average waiting time of a given

set of processes is ________.a)

FCFS scheduling algorithm.b) round robin scheduling algorithm.c) shortest job - first scheduling algorithm.

d)

shortest job - last scheduling algorithm.

181. Which of the following scheduling policy is well suited for a time-shared operating system?a) Shortest job first. b)Round robin. c)First come first serve. d)Elevator.

182 A computer installation has 1000 k of main memory. The jobs arrive and finish in the

following sequence. Job1 requiring 200k arrives Job2 requiring 350k arrives Job3 requiring

300k arrives Job1 finishes Job4 requiring 120k arrives Job5 requiring 150k arrives Job6

requiring 80k arrives Among best fit and first fit, which performs better for this sequence?

a) First fit. b)Best fit. c)Both perform the same. d)Worst fit.

183.Which of the following applications are well suited for batch processing?a)

Process control. b)Video game control.c) Preparing inventory. d)Preparing mailing addresses.

184. Locality of reference implies that the page reference being made by a process ______.

a) Will always be to the page used in the previous page reference.b) likely to be one of the pages used in the last few page references.c) Will always be one of the pages existing in the memory.d) Will always leads to a page fault.

185. The primary distinction between long term scheduler and short term scheduler is the

frequency of their________.a)

compilation. b)frequency of execution.c)debugging. d)loading.

186. An edge from process Pi to Pj in a wait for graph indicates that _____________.a) Pi is waiting for Pj to release a resource that Pi needs.

b)

Pj is waiting for Pi to release a resource that Pj needs.c) Pi is waiting for Pj to leave the system.d)

Pj is waiting for Pi to leave the system


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187. Suspended processes are written onto a _______.a) swap area. b)dedicated area. c)rom. d)critical area.

188. Which of the following system calls, does not return control to the calling point, on

termination?a)

fork. b)exec. c)ioct1. d)longjmp.

189.Which of the following are shared between a parent process and a child process?a) External Variables.b)Registers. c)Pointer variables. d)Pipes.

190. Choose the correct answer:

a) Interrupts are caused by events that are internal to a process.b) An exception condition is caused by an event external to a process.c) An exception condition happens in the middle of the exception of an instruction.d)

An interrupt happens in the middle of the execution of an instruction.

191. Using Priority Scheduling algorithm, find the average waiting time for the following set of

processes given with their priorities in the order: Process : Burst Time : Priority respectively . P1

: 10 : 3 , P2 : 1 : 1 ,P3 : 2 : 4 , P4 : 1 : 5 , P5 : 5 : 2.a)

8 milliseconds. b)8.2 milliseconds. c)7.75 milliseconds. d)3 milliseconds.

192. Which of the following is contained in Process Control Block (PCB)?a) Process Number. b)List of Open files. c)Memory Limits. d)All of the Above.

193. Which of the following is a criterion to evaluate a scheduling algorithm?a)

CPU Utilization: Keep CPU utilization as high as possible.b) Throughput: number of processes completed per unit time.c) Waiting Time: Amount of time spent ready to run but not running.d) All of the above.

194. The round robin CPU scheduling in a time-shared system is done ________.a) using very large time slice degenerates in to first come first served algorithm.

b)

using extremely small time slices improve performance.c) using extremely small time slices degenerate in to last in first out algorithm.d) using medium sized time slices leads to shortest request time first algorithm.

195. What is PCB?a) Program Control Block. b)Process Control Block.c) Process Communication Block. d)Process Common Block.

196. In Priority Scheduling a priority number (integer) is associated with each process. The CPU

is allocated to the process with the highest priority (smallest integer = highest priority). The

problem of, Starvation a low priority processes may never execute, is resolved by __________.a)

terminating the process. b)aging.c) mutual exclusion. d)semaphore.

197. The amount of work performed per unit time is _______.a) Process time. b) Output time.c) Throughput time. d) Input time.


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198. A process is said to be ________ if it is executing on a process.b) running state. b)ready state.c) blocked state. d)completed state.

199.The act of assigning the first process to the first processor on the ready list is _______.a)

dispatcher. b)dispatching.c) dispatched. d)quantum.

200 An action performed by the OS to remove a process from a processor and replace it with

another is_____.a) interrupting. b) Control switching.c) multiprocessor d)Fragmentation

201. Removing a process from a suspended state is called ____.a)

ready. b)running c)resume. d)finish.

202. An unit of time during which a process can execute before it is removed from the processor

is _____.

a)

spavn. b)quartz. c)quantum. d)trap.

203 Process isa)

program in High level language kept on diskb) contents of main memoryc)

a program in executiond) a job in secondary memorye)

None of the above

204 The strategy of allowing processes that are logically runnable to be temporarily suspended is

called

a)

preemptive scheduling b)non preemptive schedulingc) shortest job first d)first come first served e)None of the above

205. The LRU algorithma) pages out pages that have been used recently

b) pages out pages that have not been used recentlyc) pages out pages that have been least used recentlyd) pages out the first page in a given areae) None of the above

206. Thrashinga)

is a natural consequence of virtual memory systemsb)

can always be avoided by swappingc) always occurs on large computersd)

can be caused by poor paging algorithmse)

None of the above

207. Which of the following statements is false?a) the technique of storage compaction involves moving all occupied areas of storage to one end

or other of main storageb) compaction does not involve relocation of programs

c)

compaction is also know as garbage collectiond)

the system must stop everything while it performs the compactione) None of the above


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208. Interprocess communication

a) is required for all processes b)is usually done via disk drivesc) is never necessary, d)allows processes to synchronize activity

209 The CPU, after receiving an interrupt from an I/O devicea) halts for a predetermined time

b)

hands over control of address bus and data bus to the interrupting devicec) branches off to the interrupt service routine immediatelyd)

branches off to the interrupt service routine after completion of the current instructione) None of the above

210 Seeks analysisa) is used for analyzing paging problems

b)

is used for analyzing device busy problemsc) is used for analyzing control-unit busy problemsd)

is only shown on real-time displayse) None of the above

211 Consider a set of n tasks with known runtimes r1, r2, r n to be run on a uniprocessor

mmachine. Which of the following processor scheduling algorithms will result in the maximum

throughput?

a) Round-Robin b)Shortest-Job-Firstc)Highest-Response-Ratio-Next d)First-Come-First-Served

212. A process executes the codefork ();fork ();

fork ();213.The total number of child processes created is

a) 3 b) 4 c) 7 d) 8

214. consider the 3 processes, P1, P2 and P3 shown in the tableprocess Arrival time Time unit required

P1 0 5P2 1 7P3 3 4

215.The completion order of the 3 processes under the policies FCFS and RRS (round r robin

scheduling with CPU quantum of 2 time units) are

a) FCFS: P1, P2, P3 RR2: P1, P2, P3b) FCFS: P1, P3, P2 RR2: P1, P3, P2c) FCFS: P1, P2, P3 RR2: P1, P3, P2d) FCFS: P1, P3, P2 RR2: P1, P2, P3


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216. A thread is usually defined as a light weight process because an operating system (OS)

maintains smaller data structures for a thread than for a process. In relation to this, hich of the

followings is TRUE?

a) On per-thread basis, the OS maint ains only CPU register stateb)The OS does not maintain a separate stack for each threadc)On per-thread basis, the OS does not maintain virtual memory state

d)On per thread basis, the OS maintains only scheduling and accounting information.

217. Let the page fault service time be 10ms in a computer with average memory access time

being 20ns. If one page fault is generated for every 10^6 memory accesses, what is the effective

a access time for the memory?a) 21ns b) 30ns c) 23ns d) 35ns

218. An application loads 100 libraries at startup. Loading each library requires exactly one disk

a access. The seek time of the disk to a random location is given as 10ms. Rotational speed

of d disk is 6000rpm. If all 100 libraries are loaded from random locations on the disk, how

long d does it take to load all libraries? (The time to transfer data from the disk block once the

head has been positioned at the start of the block may be neglected)a) 0.50s b) 1.50s c) 1.25s d) 1.00s

219. Consider the following table of arrival time and burst time for three processes P0, P 1 and

P2.Process Arrival time Burst TimeP0 0 ms 9 msP1 1 ms 4 msP2 2 ms 9 ms

220. The pre-emptive shortest job first scheduling algorithm is used. Scheduling is c carried out

only at arrival or completion of processes. What is the average waiting t time for the three

processes?a) 5.0 ms b) 4.33 ms c) 6.33 ms d) 7.33 ms

221. Let the time taken to switch between user and kernel modes of execution be t1 while the

time taken to switch between two processes be t2. Which of the following is TRUE?

a) t1 > t2 b) t1 = t2 c) t1 < t2 d) Nothing can be said aboutthe relation between t1 and t2

222.A system uses FIFO policy for page replacement. It has 4 page frames with no pages loaded

to begin with. The system first accesses 100 distinct pages in some order and then accesses

the s same 100 pages but now in the reverse order. How many page faults will occur?

a) 196 b) 192 c) 197 d) 195

223. Which of the following statements are true?

I.Shortest remaining time first scheduling may cause starvation

II.Preemptive scheduling may cause starvation

III.Round robin is better than FCFS in terms of response time

a) I only b) I and III onlyc) II and III only d) I, II and III


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224. Consider the methods used by processes P1 and P2 for accessing their critical s

sections whenever needed, as given below. The initial values of shared boolean v

variables S1 and S2 are randomly assigned.

Method Used by P1while (S1 == S2) ;Critica1 SectionS1 = S2;

Method Used by P2while (S1 != S2) ;Critica1 SectionS2 = not (S1);

225.Which one of the following statements describes the properties achieved?

a) Mutual exclusion but not progressb) Progress but not mutual exclusionc) Neither mutual exclusion nor progressd)Both mutual exclusion and progress

226. In the following process state transition diagram for a uniprocessor system, assume that

there are always some processes in the ready state: Now consider the following statements:

I. If a process makes a transition D, it would result in another process making transition

A I immediately. II. A process P2 in blocked state can make transition E while another process

P1 is in running s state. III. The OS uses preemptive scheduling. IV. The OS uses non-

preemptive scheduling. which of the above statements are TRUE?

a) I and II b) I and III c) II and III d) II and IV

227. The enter_CS() and leave_CS() functions to implement critical section of a process a arerealized using test-and-set instruction as follows:

void enter_CS(X){while test-and-set(X) ;}void leave_CS(X){

X = 0;}

228.In the above solution, X is a memory location associated with the CS and is I initialized to

0. Now consider the following statements: 1. The above solution to CS problem is deadlock-free

2.The solution is starvation free. 3.The processes enter CS in FIFO order. 4.More than

one process can enter CS at the same time. Which of the above statements is TRUE?

a) I only b) I and II c) II and III d) IV only

229. Two processes, P1 and P2, need to access a critical section of code. Consider the following

s synchronization construct used by the processes:Here, wants1 and wants2 are shared

vvariables, which are initialized to false. Which one of the following statements is TRUE about t

the above construct?/* P1 */ while (true) { wants1 = true; while (wants2 == true); /* Critical Section*/ wants1=false; } /* Remainder section */ /* P2 */ while (true) { wants2 = true; while (wants1==true);/* Critical Section */ wants2 = false; } /* Remainder section */


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a) It does not ensure mutual exclusion.b) It does not ensure bounded waiting.c) It requires that processes enter the critical section in strict alternation.d) It does not prevent deadlocks, but ensures mutual exclusion.

230. Consider three processes (process id 0, 1, 2 respectively) with compute time bursts 2, 4 and 8

time units. All processes arrive at time zero. Consider the longest remaining time first (LRTF)sscheduling algorithm. In LRTF ties are broken by giving priority to the process with the lowest

process id. The average turn around time is:

a) 13 units b) 14 units c) 15 units d) 16 units

231. Consider three processes, all arriving at time zero, with total execution time of 10, 20 and

30 u units, respectively. Each process spends the first 20% of execution time doing I/O, the

next 70% of time doing computation, and the last 10% of time doing I/O again. The operating

s system uses a shortest remaining compute time first scheduling algorithm and schedules a

nnew process either when the running process gets blocked on I/O or when the running pprocessfinishes its compute burst. Assume that all I/O operations can be overlapped as much as possible.

For what percentage of time does the CPU remain idle?

a) 0% b) 10.6% c) 30.0% d) 89.4%

232. The atomic fetch-and-set x, y instruction unconditionally sets the memory location x to 1

and fetches the old value of x in y without allowing any intervening access to the memory

location x. consider the following implementation of P and V functions on a binary semaphore .

void P (binary_semaphore *s) {unsigned y;

unsigned *x = &(s->value);do {

fetch-and-set x, y;} while (y);}

void V (binary_semaphore *s) {S->value = 0;

}

Which one of the following is true?a) The implementation may not work if context switching is disabled in P.

b) Instead of using fetch-and-set, a pair of normal load/store can be usedc) The implementation of V is wrongd) The code does not implement a binary semaphore

233 Consider the following snapshot of a system running n processes. Process i is holding XiIinstances of a resource R, 1


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a) min (Xp, Xq) < max (Yk) where k != p and k != qb) Xp + Xq >= min (Yk) where k != p and k != qc) max (Xp, Xq) > 1d) min (Xp, Xq) > 1

234. In MS-DOS 5.0, which is the number that acts as a code to uniquely identify the software

product?

a) MS b) DOS c) MS DOS c) 5.0 e) None of the above

235 Consider the following code fragment:if (fork() == 0){ a = a + 5; printf(%d,%d\n, a, &a); }else { a = a5; printf(%d, %d\n, a, &a); }

Let u, v be the values printed by the parent process, and x, y be the values printed b y the

child process. Which one of the following is TRUE?(a) u = x + 10 and v = y (b) u = x + 10 and v != y(c) u + 10 = x and v = y (d) u + 10 = x and v != y

236. Fetch_And_Add(X,i) is an atomic Read-Modify-Write instruction that reads the v alue

of memory location X, increments it by the value i, and returns the old value of X. It is used

in the pseudocode shown below to implement a busy-wait lock. L is an u nsigned integer

shared variable initialized to 0. The value of 0 corresponds to lock b eing available, while any

non-zero value corresponds to the lock being not available.AcquireLock(L){

while (Fetch_And_Add(L,1))L = 1;

}ReleaseLock(L){

L = 0;}

This implementationa) fails as L can overflow

b) fails as L can take on a non-zero value when the lock is actually availablec) works correctly but may starve some processesd) works correctly without starvation

237 Which scheduling policy is most suitable for a time-shared operating systems?a) Shortest Job First b) Round Robinc) First Come First Server d)Elevator

238. Consider a set of n tasks with known runtimes r1, r2, rn to be run on a uniprocessor

machine. Which of the following processor scheduling algorithms will result in the m

maximum throughput?a) Round-Robin b) Shortest-Job-Firstc) Highest-Response-Ratio-Next d)First-Come-First-Served

239. Which of the following scheduling algorithms is non-preemptive?(a) Round-Robin(b) First In First Out

(c) Multilevel Queue Scheduling(d) Multilevel Queue Scheduling with Feedback


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240 Consider three CPU-intensive processes, which require 10, 20 and 30 time units and a

arrive at times 0, 2 and 6, respectively. How many context switches are needed if the

operating system implements a shortest remaining time first scheduling algorithm? Do

not count the context switches at time zero and at the end.

(a) 1 (b) 2 (c) 3 4

241. Group 1 contains some CPU scheduling algorithms and Group 2 contains some a

applications. Match entries in Group 1 to entries in Group 2.

Group I Group II

(P) Gang Scheduling (1) Guaranteed Scheduling

(Q) Rate Monotonic Scheduling (2) Real-time Scheduling

(R) Fair Share Scheduling (3) Thread Scheduling(a) P3 Q2 R1(b) P1 Q2 R3(c) P2 Q3 R1(d P1 Q3 R2

242. Assume that the following jobs are to be executed on a single processors system-----------------------Job-Id CPU-BurstTime-----------------------p 4q 1r 8s 1t 2

-----------------------

243. The jobs are assumed to have arrived at time 0 and in the order p, q, r, s, t. Calculate thedeparture time (completion time) for job p if scheduling is round robin with time slice 1.(a) 4 (b) 10 (c) 11 (d) 12

244. An operating system uses Shortest Remaining Time first (SRT) process scheduling

algorithm. Consider the arrival times and execution times for the following processes:-------------------------------------Process Execution time Arrival time-------------------------------------P1 20 0P2 25 15P3 10 30P4 15 45-------------------------------------

245. What is the total waiting time for process P2?(a) 5 (b) 15 (c) 40 (d) 55


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246. Which is the component of a file system concerned with providing the mechanisms is files to

be stored, to be referenced, shared and secured is ________.a). File reorganization. b). File integrity mechanismc). File management. d). File system.

247. SJF stands for _________.

a) shortest job for. b). shortest job last. c). Shortest job middle. d). shortest job first.

248. SJF is not useful in _____ environments in which reasonable response times much be

guaranteed.a). real time. b). time sharing. c). online. d). multiprogramming.

249 _______ is the system response time to the job if the job were to be initiated.a) Time waiting. b). Service time.c). Time waiting + service time. d). System time.

250. Which one of the following is not a characteristic of a file system?a) File management. b) File integrity mechanism.c) File access methods. d). File sizing.

251. Round Robin is _______ type of scheduling.a) Preemptive. b) Non-preemptive. c) time sharing. d). real time.

252. SRT has ____ overhead than SJF.a). lower . b) medium. c) higher. d) none.

253. _____ is not useful in scheduling interactive uses because it cannot guarantee good responsetime.A. SJF.B. SRT.C. FIFO.D. LIFO.

254. Processes are dispatched FIFO but are given a limited amount of CPU time called_____.a). RR. b) time - slice or quantum. c) SJF. d) HRN.

255. Round Robin is _______ type of scheduling.a) preemptive. b) non-preemptive. c) time sharing. d) real time.

256. SRT has ____ overhead than SJF.a) lower . b)medium. c) higher. d) none.

257. In _______scheduling, certain jobs are scheduled to be completed by a specific time or

deadline.a) processor scheduling. b) job scheduling.c) deadline scheduling. d) real time scheduling.

258. The simplest scheduling discipline is ____________.

a) FIFO. b) RR. c). SJF. d)SRT.


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259 . _______ is a non-preemptive discipline.

a) Quantum size. b). HRN c). FIFO. d) LIFO.

260. Keeping non-running programs is main storage involves______.a) No overhead. b) page faults. c) overhead. d) page default.

261. Preemptive scheduling is useful in ______.a.) interactive timesharing systems. b) real- time systems.c) Multiprogramming systems. d) On-line systems.

262. The problems of determining when processors should be assigned and to which processes.

This is called_____.a) processor scheduling b) job scheduling.c) high-level scheduling. d) low-level scheduling.

263. A scheduling discipline is ___________ if once a process has given the CPU.

a) preemptive. b) non-preemptive.c). real time. d) on line.

264. A scheduling discipline is _____if the CPU can be taken away.A. non-preemptive. B. preemptive.C. timesharing. D. multiprogramming.

265_______ contains the highest address used by the operating system.A. Coalescing. B. Boundary register.

C. Garbage collection. D. Overlays.

266.Thrashing occurs ________.A. when excessive swapping takes place. B. when you thrash your computer.C. whenever deadlock occurs. D. when no swapping takes place.

267..Dijkstra banking algorithm in an operating system solves the problem of _______.A. deadlock avoidance. B. deadlock recovery.C. mutual exclusion. D. context switching.

268. A state is safe if the system can allocate resources to each process(up to its maximum) in

some order and still avoid deadlock ________.A. deadlocked state is safe. B. safe state may lead to a deadlock situation.C. unsafe state must lead to a deadlock situation. D. deadlocked state is a subset of unsafe state.

269.A state is safe, if ___________.A. the system does not crash due to deadlock occurrence.B. the system can allocate resources to each process in some order and still avoid a deadlock.C. the state keeps the system protected and safe.D. All of above.


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270.If no cycle exists in the resource allocation graph ____________.

A. then the system will be in a safe state.B. then the system will not be in a safe state.C. either a or b.D. None of these.

271.The Bankers algorithm is _____________ than the resource allocation graph algorithm. A. less efficient. B. more efficient.C. effective D. None of these.

272 .The host repeatedly checks if the controller is busy until it is not. It is in a loop that status

register &busy bit becomes clear. This is called _____________ and a mechanism for the

hardware controller tonotify the CPU that it is ready is called ___________.A. interrupt and polling. B. polling and spooling.C. polling and interrupt. D. deadlock and starvation.

273..If the wait for graph contains a cycle ___________.

A. then a deadlock does not exist. B. then a deadlock exists.C. then the system is in a safe state. D. either b or c.

274 .The disadvantage of invoking the detection algorithm for every request is ____________.A. overhead of the detection algorithm due to consumption of memory.B. excessive time consumed in the request to be allocated memory.C. considerable overhead in computation time.D. All of these.

275.Deadlock prevention is a set of methods __________.A. to ensure that at least one of the necessary conditions cannot hold.

B. to ensure that all of the necessary conditions do not hold.C. to decide if the requested resources for a process have to be given or not.D. to recover from a deadlock.

276 .Dijktra Barker Algorithm is an example for ____.A. deadlock prevention. B. deadlock detection.C. deadlock avoidance. D. deadlock recovery.

277 .What problem is solved by Dijkstra's banker's algorithm?

A) mutual exclusion B) deadlock recovery

C) deadlock avoidance D) cache coherenceE) None of the above

278.The dispatcherA) actually schedules the tasks into the processorB) puts tasks in I/O waitC) is always small and simpleD) never changes task prioritiesE) None of the above


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279. Which of the following is NOT a valid deadlock prevention scheme?a) Release all resources before requesting a new resource(b) Number the resources uniquely and never request a lower numbered resource than the last onerequested.(c) Never request a resource after releasing any resource(d) Request and all required resources be allocated before execution.

280. Let m[0]m[4] be mutexes (binary semaphores) and P[0] . P[4] be processes.

Suppose each process P[i] executes the following:wait (m[i]); wait(m[(i+1) mode 4]);release (m[i]); release (m[(i+1)mod 4]); This could cause (GATE CS 2000)

a) Thrashing (b Deadlockc) Starvation, but not deadlock d) None of the above

281. Consider Petersons algorithm for mutual exclusion between two concurrent p Processes i

and j. The program executed by process is shown below. repeat

flag [i] = true;

turn = j;

while ( P ) do no-op;

Enter critical section, perform actions, then exit criticalsection

flag [ i ] = false;

Perform other non-critical section actions.

until false; For the program to guarantee mutual exclusion, the predicate P in the while loop s

should be

a) flag [j] = true and turn = ib) flag [j] = true and turn = jc) flag [i] = true and turn = jd) flag [i] = true and turn = i

282.Which of the following is NOT true of deadlock prevention and deadlock avoidance

schemes?(a) In deadlock prevention, the request for resources is always granted if the resulting state is safe(b) In deadlock avoidance, the request for resources is always granted if the result state is safe(c) Deadlock avoidance is less restrictive than deadlock prevention(d) Deadlock avoidance requires knowledge of resource requirements a prioriTo avoid the race condition, the number of processes that may be simultaneously inside their criticalsection isA) 8 B) 1 C) 16 D) 0E) None of the above

283. Dijktra Barker Algorithm is an example for ____.A. deadlock prevention. B. deadlock detection.C. deadlock avoidance. D. deadlock recovery.

284. A binary semaphore ____________.A. has the values one or zero. B. is essential to binary computers.C. is used only for synchronization. D. is used only for mutual exclusion.

285.The section of code which accesses shared variables is called as __________.A. critical section. B. block.C. procedure. D. semaphore.


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286. _____ is a high level abstraction over Semaphore.A. Shared memory. B. Message passing.C. Monitor. D. Mutual exclusion.

287_____ is a high level abstraction over Semaphore.A. Shared memory. B. Message passing.C. Monitor. D. Mutual exclusion.

288 The initial value of the semaphore that allows only one of the many processes to enter

their critical sections, isA) 8 B) 1 C) 16 D) 0 E) None of the above

289. Producer consumer problem can be solved usingA) semaphores B) event counters C) monitorsD) all of the above E) None of the above

290.The P and V operations on counting semaphores, where s is a counting semaphore, are

defined as follows:P(s) : s = s - 1;if (s < 0) then wait;V(s) : s = s + 1;

if (s


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292 A process executes the following code

for (i = 0; i < n; i++) fork();

The total number of child processes created is(A) n (B) 2^n1 (C) 2^n (D) 2^(n+1) - 1;

293. Distributed OS works on the ________ principle.

A. file foundation. B. single system image.C. multi system image. D. networking image.

294. Which directory implementation is used in most Operating System?

A. Single level directory structure. B. Two level directory structure.C. Tree directory structure. D. Acyclic directory structure.

295. Boundary registers ________.A. are available in temporary program variable storage.B. are only necessary with fixed partitions.C. track the beginning and ending the program.

D. track page boundaries.

296. Resource locking ________.A. allows multiple tasks to simultaneously use resource.B. forces only one task to use any resource at any time.C. can easily cause a dead lock condition.D. is not used for disk drives.

297. A tree structured file directory system ____________.

A. allows easy storage and retrieval of file names.B. is a much debated unnecessary feature.

C. is not essential when we have millions of files.D. allows easy storage and retrieval of directory names.

298. In the ___________ method of data transfer, the participation of the processor is eliminated

during data transfer.

A. buffering. B. caching.C. direct memory access. D. indirect memory access.

299. Spatial locality refers to the problem that once a location is referenced, _______________.A. it will not be referenced again. B. it will be referenced again.C.a nearby location will be referenced soon. D. will be referenced later.

300.Sector interleaving in disks is done by ________.A. the disk manufacturer. B. the disk controller cord.C. the operating system. D. hardware.

301.A computer system have 6 tape drives, with n processes competing for them. Each process

may need 3 tape drives. The maximum value of n for which the system is guaranteed to be

deadlock free is _______.A. 2 B. 3 C. 4 D. 1


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302 .In which of the following directory system, is it possible to have multiple complete paths for

a file,starting from the root directory?

A. Single level directory. B. Two level directory.C. Tree structured directory. D. Acyclic graph directory.

303. A certain moving arm disk storage with one head has following specifications: Number of

tracks/recording surface-200 Disk rotation speed = 2400 rpm Track Storage capacity = 62500

bits What is the transfer rate?A. 2.5Mbits/s. B. 4.25Mbits/s.C. 1.5 Mbits/s. D. 3.75Mbits/s.

304.A computer system has 4 K word cache organized in a block-set-associative manner, with 4

blocks per set, 64 words per block. The number of bits in the SET and WORD fields of the main

memory addressformat is ________.A. 15,4. B. 6,4.C. 7,2. D. 4,6.

305. Which is the least level partition of disk?

A. Clusters. B. Sectors.C. Slides. D. Tracks.

306.Swapping _______.A. works best with many small partitions.B. allows many programs to use memory simultaneously.C. allows each program in turn to use the memory.D. does not work with overlaying.

307.The problem of thrashing is affected scientifically by ________.A. program structure. B. program size.

C. primary storage size. D. secondary storage size.

308. RAID level 3 supports a lower number of I/Os per second, because _______________.A. every disk has to participate in every I/O request.B. only one disk participates per I/O request.C. I/O cycle consumes a lot of CPU time.D. All of these.

309. Name the disk scheduling strategy that next services the request that is closest to the read-

write head currents cylinder.A. SDTP disk scheduling. B. FSCAN disk scheduling.C. C SCAN disk scheduling. D. SSTF disk scheduling.

310.The smallest portion of a track that can be accessed by an I/O request is ____.A. Sector. B. Partition. C. Blocks. D. Tracks.

311.The time it takes for the read/write head to move from its current cylinder to the cylinder

containing the requested data saved is _________.A. Seek time. B. Sector queering. C. Seek operation. D. Seek interval.


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312 What is the area of disk where boundaries cannot be crossed by file data?

A. Sectors. B. Partition. C. Portion. D. Blocks.

313.What is the average time a system spends waiting for a disk request is to be received?A. Mean time to failure. B. Mean response time.C. Response time. D. Request time.

314.In FSCAN disk scheduling, the F stands for __________.A. Forward. B. Freezing.C. Fragmentation. D. Frequently.

315.Which reduces unfairness and variance of response time as compare to SSTP?A. SCAN disk scheduling. B. Look disk scheduling.C. Disk scheduling. D. Disk processing.

316.What is the pattern that has series of request is cylinder randomly distributed access disk

surfaces?

A. Seek operating. B. Memory.C. Random seek pattern. D. System.

317 A technique that orders disk requests is maximize throughput and minimize residence times

and the variance of seek time.A. Disk scheduling. B. C- SCAN disk scheduling.C. D - SCAN. D. Disk arm.

318.Name the data redundancy technique in RAID that maintains a copy of each disks contents

on separate disk.A. Disk moving. B. Disk copying.

C. Disk mirroring. D. Disk spacing.

319. Which method can reduce access times when reading from or writing to file sequentially?A. Data compression. B. Data recognition.C. Fragmentation. D. Disk aim anticipation.

320_____ are set of tracks that can be accessed by read / write head.A. Cylinder. B. Sector.C. Boom. D. Tracks.

321____ strategy begins each search for an available hole at the point where the search ended.A. Best-fit. B. First-fit.C. Forward-fit. D. Next-fit.

322 The time taken by the disk arm to locate the specific address of a sector for getting

information is called__________.A. rotational latency. B. seek time.C. search time. D. response time.


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323 Virtual memory is __________.A. an extremely large main memory.B. an extremely large secondary memory.C. an illusion of extremely large main memory.D. a type of memory used in super computers.

324. Paging _________.A. solves the memory fragmentation problem.B. allows modular programming.C. allows structured programming.D. avoids deadlock.

325. The problem of fragmentation arises in ________.A. static storage allocation.B. stack allocation storage.C. stack allocation with dynamic binding.D. heap allocation.

326. The principle of locality of reference justifies the use of ________.A. virtual memory. B. interrupts.C. main memory. D. cache memory.

327. In paging, physical memory is broken into fixed-sized blocks called ___________.A. pages. B. frames.C. blocks. D. segments.

328. Semaphore can be used for solving __________.

A. wait & signal. B. deadlock.C. synchronization. D. priority.

329. Mechanism of bringing a page into memory when it is needed is called _______.A. segmentation. B. fragmentation.C. demand paging. D. page replacement.

330. _________ page replacement algorithm suffers from Belady anamoly.A. LRU. B. MRU. C. FIFO. D. LIFO.

331. The page replacement policy that sometimes leads to more page faults when the size of the

memory increased is ______.A. FIFO. B. LRU. C. SSTF. D. SJF.

332. In paged memory systems, if the page size is increased, then the internal fragmentation

generally _____.A. becomes less. B. becomes more.C. remains constant. D. not remains constant.

333. If the property of locality of reference is well pronounced in a program ____________.A. the number of page faults will be more.B. the number of page faults will be less.

C. the number of page faults will remain the same.D. execution will be slower.


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334. Disk scheduling involves deciding ________.A. which disk should be accessed next.B. the order in which disk access requests must be serviced.C.the physical location where files should be accessed in the disk.D. the physical location where files should be accessed in the main memory.

335. Dirty bit is used to show the ______.

A. page with corrupted data.B. wrong page in the memory.C. page that is modified after being loaded into cache memory.D. page that is less frequently accessed.

336. Fence register is used for _______.A. cpu protection. B. memory protection.C. file protection. D. disk protection.

337. In a paged memory, the page hit ratio is 0.35, the time required to access a page in

secondary memory is equal to 100 ns. The time required to access a page in primary memory is10ns. The average time required to access a page is ________.

A. 3.0ns. B. 68.0 ns.C. 68.5 ns. D. 78.5 ns.

338. The size of the virtual memory depends on the size of the ______.A. data bus. B. main memory.C. address bus. D. secondary memory.

339. In a system that does not support swapping _________.A. binding of symbolic addresses to physical addresses normally takes place during

compilation.B. he compiler normally binds symbolic addresses to physical addresses.C. the loader binds re locatable addresses to physical addresses.D. binding of symbolic addresses to physical addresses normally takes place during execution.

340. Which of the following is true?A. Overlays are used to increase the size of physical memory.B. Overlays are used to increase the logical address space.C. When overlays are used, the size of a process is not limited to the size of physical memory.D. Overlays are used whenever the physical address space is smaller than the logical addressspace.

341. In partitioned memory allocation scheme, the ________.A. best fit algorithm is always better than the first fit algorithm.B. first fit algorithm is always better than the best fit algorithm.C. superiority of the first fit and best-fit algorithms depend on the sequence of memoryrequests.D. superiority of the first fit and best-fit algorithms depend on the sequence of process requests.

342. The main function of shared memory is to _________.A. use primary memory efficiently. B. do intra process communication.

C. do inter process communication. D. use secondary memory efficiently.


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343. Aging is _______.

A. keeping track of cache contents.B. keeping track of what pages are currently residing in the memory.C. keeping track of how many times a given page is referenced.D. increasing the priority of jobs to ensure termination in a finite time.

344. If there are 32 segments, each of size 1 kbytes, then the logical address should have ______A. 13 bits. B. 14 bits. C. 15 bits. D. 16 bits.

345. In a paged segmented scheme of memory management, the segment table itself must have a

page table because _______.A. the segment table is often too large to fit in one page.B. each segment is spread over a number of pages.C. segment tables point to page tables and not to the physical location of the segment.D. the processor description base register points to a page table.

346. A memory page containing a heavily used variable that was initialized very early and is inconstant use is removed. When the page replacement algorithm used is _______.

A. LRU. B. FIFO. C. LFU. D. SJF.

347. Consider a computer with 8Mbytes of main memory and a 128K cache. The cache block size

is 4 K. it uses a direct mapping scheme for cache management. How many different main

memory blocks can map onto a given physical cache block?A. 20. B. 25. C. 64. D. 456.

348. The content of the matrix Need is __________.A. AllocationAvailable. B. MaxAvailable.

C. MaxAllocation. D. AllocationMax.

349. Virtual memory allows ___________.A. execution of a process that may not be completely in memory.B. a program to be larger than the cache memory.C. a program to be larger than the secondary storage.D. execution of a process without being in physical memory.

350. When a page fault occurs, the state of the interrupted process is ___________.A. disrupted B. invalid C. saved D. None of these

351. When the page fault rate is low ________.A. the turnaround time increases. B. the effective access time increases.C. the effective access time decreases. D. a and b.

352. VirtualMemory is commonly implemented by __________.A. segmentation. B. swapping. C. demand Paging. D. demand line.

353. MemoryA) is a device that performs a sequence of operations specified by instructions in memory.B) is the device where information is storedC) is a sequence of instructionsD) is typically characterized by interactive processing and time-slicing of the CPU's time to allow

quick response to each user.


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354. A system program that sets up an executable program in main memory ready for

execution isA) assembler B) linker C) loader D) compiler

355 Which of the following are loaded into main memory when the computer is booted?A) internal command instructions B) external command instructions

C) utility programs D) word processing instructionsE) None of the above

356 The FIFO algorithm

A) executes first the job that last entered the queueB) executes first the job that first entered the queueC) execute first the job that has been in the queue the longestD) executes first the job with the least processor needsE) None of the above

357 The principal of locality of reference justifies the use of

A) reenterable B) non reusableCvirtual memory D) cache memoryE) None of the above

358 The register or main memory location which contains the effective address of the operand

is known asA) pointer B) indexed register C) special locationD) scratch pad E) None of the above

359.Thrashing can be avoided ifA) the pages, belonging to the working set of the programs, are in main memory

B) the speed of CPU is increasedC) the speed of I/O processor is increasedD) all of the aboveE) None of the above

360. Resolution of externally defined symbols is performed byA) Linker B) Loader C) CompilerD) Assembler E) None of the above

361 System generation:A) is always quite simple B) is always very difficult C) varies in difficulty between systemsD) requires extensive tools to be understandable E) None of the above

362. The Memory Address Register

A) is a hardware memory device which denotes the location of the current instruction being executed.B) is a group of electrical circuits (hardware), that performs the intent of instructions fetched from

memory.C) contains the address of the memory location that is to be read from or stored into.D) contains a copy of the designated memory location specified by the MAR after a "read" or the new

contents of the memory prior to a "write".

E) None of the above

363 In virtual memory systems, Dynamic address translation


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A) is the hardware necessary to implement pagingB) stores pages at a specific location on diskC) is useless when swapping is usedD) is part of the operating system paging algorithmE) None of the above

364. Fragmentation of the file system

A) occurs only if the file system is used improperlyB) can always be preventedC) can be temporarily removed by compactionD) is a characteristic of all file systemsE) None of the above

365. A non-relocatable program is one whichA) cannot be made to execute in any area of storage other than the one designated for it at the

time of its coding or translation.B) consists of a program and relevant information for its relocation.C) can itself performs the relocation of its address-sensitive portions.

D) all of the aboveE) None of the above

366 In which addressing mode the effective address of the operand is the contents of a register

specified in the instruction and after accessing the operand, the contents of this register is

incremented to point to the next item in the list?A) index addressing B) indirect addressing

C) auto increment D) auto decrementE) None of the above

367 The memory allocation scheme subject to "external" fragmentation is

A) segmentation B) swappingC) pure demand paging D) multiple contiguous fixed partitionsE) None of the above

368. While working with MS-DOS, which command will you use to transfer a specific file from

one disk to another?

A) DISKCOPY B) COPY C) RENAME D) FORMATE) None of the above

369. In which addressing mode the contents of a register specified in the instruction are first

decremented, and then these contents are used as the effective address of the operands?

A) index addressing B) indirect addressing C) auto incrementD) auto decrement E) None of the above

370. Page stealingA) is a sign of an efficient system B) is taking page frames from other working setsC) should be the tuning goal D) is taking larger disk spaces for pages paged outE) None of the above


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371. In MS-DOS 5.0, which is the number that acts as a code to uniquely identify the software

product?

A) MS B) DOS C) MS DOS D) 5.0 E) None of the above

372 Memory management is :A) not used in modern operating system B) replaced with virtual memory on current systems

C) not used on multiprogramming systems D) critical for even the simplest operating systems


373 The Register - to - Register (RR) instructionsA) have both their operands in the main store.B) which perform an operation on a register operand and an operand which is located in the main store,

generally leaving the result in the register, except in the case of store operation when it is alsowritten into the specified storage location.

C) which perform indicated operations on two fast registers of the machine and leave the result in oneof the registers.

D) all of the aboveE) None of the above

374. A page faultA) is an error is a specific page B) occurs when a program accesses a page of memoryC) is an access to a page not currently in memoryDis a reference to a page belonging to another programE) None of the above

375. The process of transferring data intended for a peripheral device into a disk (or

intermediate store) so that it can be transferred to peripheral at a more convenient time

or in bulk, is known asA) multiprogramming B) spooling C) caching D) virtual programming


376. Block caches or buffer caches are usedA) to improve disk performanceB) to handle interruptsC) to increase the capacity of the main memoryD) to speed up main memory read operationE) None of the above

377. Which of the following statements is false?A) a small page size causes large page tablesB) internal fragmentation is increased with small pagesC) a large page size causes instructions and data that will not be referenced brought into

primary storageD) I/O transfers are more efficient with large pagesE) None of the above

378. Which of the following is false about disk when compared to main memory?A) non-volatile B) longer storage capacityC) lower price per bit D) fasterE) None of the above

379. If the number of bits in a virtual address of a program is 12 and the page size is 0.5 K

bytes, the number of pages in the virtual address space is


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A) 16 B) 32C) 64 D) 128E) None of the above

380. SwappingA. works best with many small partitionsB.allows many programs to use memory simultaneously

C. allows each program in turn to use the memoryD.does not work with overlayingE. None of the above

381. A disk scheduling algorithm in an operating system causes the disk arm to move back and

forth across the disk surface in order to service all requests in its

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